1. Field of the Invention
The present invention relates to a mobile communication terminal to support video calling, and more particularly, to a method for encoding video call data capable of efficient data encoding.
2. Description of the Background Art
A protocol for multiplexing audio data, control data, and video data when performing video calling using a mobile communication device (e.g. a mobile communication terminal for supporting Wideband Code Division Multiple Access (WCDMA)) includes H.223. The H.223 protocol was proposed by the International Telecommunications Union—Telecommunication Standardization Sector (ITU-T). This protocol comprises an adaptation layer for detecting an error and restoring the detected error, and a multiplex layer for forming audio data and video data as one data unit. The multiplex layer reconstructs data with a certain ratio by using a multiplex code formed for H.245 signaling with reference to a multiplex code table, and then transmits the data to a network (Fixed Multiplex Code Selection).
FIG. 1 shows an exemplary view of a method for encoding video call data for a mobile communication terminal in accordance with the related art.
A mechanism for selecting a code from a multiplex code table for encoding data will be explained. In the related art, a code selection was performed by two WCDMA mobile terminals under a fixed selection mechanism. Referring to FIG. 1, a fifth multiplex code is selected from the multiplex code table by a mobile communication terminal according to the H.245 signaling. The fifth multiplex code of the multiplex table indicates the sequentially encoding of voice data (LCN1) of 4 bytes (RC4), control data (LCN2) of 1 byte (RC1), and video data (LCN3) of 2 bytes (RC2).
Accordingly, when substantially inputted data includes voice data of 4 bytes, control data of 3 bytes, and video data of 3 bytes, the voice data of 4 bytes is loaded, then the control data of 1 byte is loaded, and then the video data of 2 bytes is loaded. Next, the control data of 1 byte is loaded, and the video data of 1 byte is loaded. Then, the remaining 1 byte of the control data is loaded into a next packet.
However, the related art method for encoding video call data has a problem that an amount of data is not controlled according to a state of a wireless network. That is, in the related art method, enhancing a data quality by maintaining the wireless network as an optimum state by decreasing the amount of data when the wireless network is not in an optimum state and by increasing the amount of data when the wireless network is in an optimum state can not be performed.
Also, in case of using the H.223 protocol, a data bias phenomenon in which only one type of data, either audio or video, is transmitted at a specific time point in time is generated, and thus the audio data and the video data are not consistent with each other. That is, the audio data and the video data can not be re-adjusted into a proper ratio. Therefore, when either the audio data and the video data is transmitted, the synchronization between the audio data and the video data is inconsistent with each other. For instance, during video reproduction (playback), the images of a person who appears to be speaking may not match the audio being reproduced, namely, the person's lips and his voice may not correspond with each other.